Closed-form solution and parametric study on lateral dynamic response of pile-type bridge piers resting on cement-soil composite pipe piles

Abstract

This paper develops a closed-form analytical framework for the lateral dynamic interaction between a pile-type bridge (PTB) pier and a cement-soil composite (CC) pipe pile in viscoelastic soil, based on Timoshenko beam theory. The derived analytical solutions are rigorously verified through two parallel approaches: comparison with published theoretical results and cross-validation against PLAXIS 3D numerical simulations. On this basis, systematic parametric analyses are conducted to quantify the influences of key parameters of the PTB pier, cement-soil pile and PHC pipe pile on the lateral dynamic response of the coupled system. The results reveal that piers with smaller heights deliver stronger low-frequency load-bearing performance but face a higher risk of resonance under high-frequency excitation, whereas taller piers can effectively postpone the occurrence of resonant peaks. Enlarging the reinforcement radius and elastic modulus of the cement-soil pile, as well as increasing the outer radius and elastic modulus of the inner PHC pipe pile, all improve the lateral vibration resistance of the entire coupled system. In particular, increasing the structural mass at the pier top amplifies the horizontal inertial force of the system, which adversely affects the lateral vibration resistance of the coupled pile-pier system.